Ceanothus thyrsiflorus, known as blueblossom or blue blossom ceanothus, is an evergreen shrub in the buckthorn family Rhamnaceae that is endemic to Oregon and California in the US. The term 'Californian lilac' is also applied to this and other varieties of ceanothus, though it is not closely related to Syringa, the true lilac.
Ceanothus thyrsiflorus can grow more than 6m (20feet) tall and broad in its native chaparral habitat, with glossy green leaves. The clusters of tiny flowers, borne in spring, vary from different shades of blue to close to white.[1] The evergreen leaves are shiny and about 4cm (02inches) long.[2]
The Latin genus name Ceanothus is derived from the Ancient Greek, (; 'spiny plant'). The name was originally used by Theophrastus for another plant, and Linnaeus reused it for Ceanothus.[3]
The Latin specific epithet thyrsiflorus is derived from the Ancient Greek (; meaning a 'contracted panicle, wreath, or thyrsos') and the Latin (gen. 'flower'), and so, thyrsiflorus means approximately 'with flowers arranged in the shape of a contracted panicle or thyrsos staff'.
It is popular with birds, butterflies, and other pollinators. It is often visited by honeybees for its pollen.
Ceanothus thyrsiflorus has been used in gardens extensively. It prefers a warm, sheltered position in full sun.[4] Several cultivars have been selected, including: